#include <iostream>
using namespace std;
void square(float&x,float&y){x=x*x;y=y*y;}
void cube(float&x,float&y){x=x*x*x;y=y*y*y;}
typedef void(*p)(float&,float&);
void print(p vp,float&x,float&y)
{
	cout<<"执行函数前\n";
	cout<<"x:"<<x<<"\t"<<"y:"<<y<<endl;
	vp(x,y);
	cout<<"执行函数后\n";
	cout<<"x:"<<x<<"\t"<<"y:"<<y<<endl;
}
void Swap(float&x,float&y){int z;z=x;x=y;y=z;}
int main()
{
	float a=2,b=3;
	char choice='0';
	int i;
	//void (*p[5])(float&x,float&y);
	p vp;
	for (i=0;i<5;i++)
	{
		cout<<"(0)退出(1)平方(2)立方(3)交换x和y的值：";
		cin>>choice;
		bool quit=false;
		switch (choice)
		{
		case'0':quit=true;break;
		case'1':vp=square;break;
		case'2':vp=cube;break;
		case'3':vp=Swap;break;
		default:vp=0;
		}
		if(quit)break;
		if(vp==0)
		{
			cout<<"请输入一个从0到3之间的数字\n";
			i=i-1;
			continue;
		}
		print(vp,a,b);
	}
	return 0;
}